In recent years, addition of various nanomaterials to a driving mechanism, such as an engine, and a transmission mechanism, such as a transmission gear and a reduction gear, has been studied for purposes of improving fuel consumption, reducing friction, and the like. In particular, for environmental or resource problems, carbon materials such as graphene, CNT (carbon nanotube) and fullerene have attracted attention as nonmetal nanomaterials.
Taking engine oil as an example, addition of molybdenum disulfide (MoS2) or flaky graphite having a layered crystal structure, which exhibit low shearing resistance, and the like has been known (Non Patent Literature 5). Further, a sliding member in which a friction loss is further reduced on a sliding surface by using graphite in a particulate form has been studied (Patent Literature 1).
On the other hand, as for lubricants, for a purpose of prolonging the life of a lubricant by suppressing deterioration of the base oil itself caused by a temperature change, oxidation, and the like, addition of carbon materials, such as carbon fibers and carbon nanotubes, having an antioxidative effect and a decomposition/deterioration preventive effect for base oil, and radioactive substances generating a negative ion and the like has been studied (Patent Literatures 2, 3 and 4).